In the field of rotary die cutting, corrugated board, or like material to be cut, is fed into the nip of a pair of rotating rollers, wherein one roller is equipped with radially extending cutting edges, and the other roller (the "anvil") is equipped with a surface upon which the cutting edges of the die may bear during the cutting operation. The outer surface of the anvil preferably is a replaceable cover of thermosetting but resilient material such as polyurethane plastic, and the like. Resilient anvil covers may be made in a continuous circle (tube-like), with the cover being pushed longitudinally upon the anvil base (as a ring is placed on a finger). However, it has been found desirable from the standpoint of mounting an anvil cover on a base anvil member, to employ a unitary cover which may be wrapped around the base member and locked in place. This permits the said cover to include and employ circumferential disposed integral ribs, extending radially inwardly from the cover inner surface so to engage appropriately positioned circumferential grooves (slots) in the outer arcuate surfaces of the support member.
Anvil covers of this type may be provided in two or more pieces, the ends of which may similarly interlock or, as a single length, the two ends thereof also being adapted to interlock when the cover is mounted on the base anvil member. A successful interlocking system is shown in U.S. Pat. No. 3,522,754 (1970), wherein mating ends of the anvil cover are provided with alternating lugs and recesses of the depicted form. In mounting an anvil cover of this type upon a support, the cover is wrapped upon the support and the interlocking ends are merely pressed together to provide a strong seam. U.S. Pat. No. 3,577,822 (1971) described a two element resilient cover.
It is desired that an anvil cover be capable of withstanding many thousands of cutting operations before the eventual replacement thereof is necessary. Further, it is desired that the entire surface of the anvil cover be available for use, including the area wherein the seams between connecting (interlocked) cover ends are located. The dual seams of two element covers complicate this functional objective. The present configuration obviates the largely cut out midline that becomes the fatigue line of the prior art covers.